Re: Make sure numbers are numbers

["Stuart P. Bentley" <stuart@...>]

One case where I've actually encountered unavoidable issues with a Lua  
design due to type coercion was something like this, if I recall correctly:

num_table{[2]="This gets printed instead"}

index_searched_for="2"

print(num_table[index_searched_for] or "Even though this is what should be  
printed!")

If I've got that right and am not mis-remembering the problem, then Lua  
5.2 should make the change that type coercion never comes into play when  
indexing tables.

On Thu, 15 Apr 2010 21:07:21 -0600, Henk Boom <henk@henk.ca> wrote:

> I just fixed a subtle bug in my serialization/deserialization
> functions for a data structure, where objects that were serialized
> then deserialized looked identical but behaved slightly differently.
> It was caused by something like this:
>
> > return 9 < 10
> true
> > return "9" < "10"
> false
>
> Lesson learned: make sure to use tonumber() on numbers you extract
> from strings...
>
> It also boost the importance of frequent type checking in my mind, and
> makes me hate automatic string->number coercion a little bit more :p
>
>     henk